[PATCH v1] shebang: restrict python interactive prompt/interpreter

Matt Brown matt at nmatt.com
Fri Jun 9 16:37:50 UTC 2017

On 6/9/17 11:41 AM, Tetsuo Handa wrote:
> Matt Brown wrote:
>>> What about execution via ld-linux ?
>>>    $ /lib64/ld-linux-x86-64.so.2 /usr/bin/python2
>> Just tested this and you are correct, this allows you to bypass the
>> protection.
>> I was able to fix this bypass by including /lib64/ld-linux-x86-64.so.2
>> in the list of interpreters.
> And there is also PYTHONINSPECT environment variable. ;-)
> # echo '#!/usr/bin/python2' > run-python
> # chmod 755 run-python
> # ./run-python
> # PYTHONINSPECT=yes ./run-python
>>>> print "hello"
> hello

While this bypass works against this LSM alone, when combined with
Trusted Path Execution this is prevented for non-root/untrusted user.
This is why I feel like this is such a great feature to combine with TPE
as I said here:


Results from my test:

$ PYTHONINSPECT=yes ./run-python

-bash: ./run-python: /usr/bin/python2: bad interpreter: Operation not

and in the dmesg log:
TPE: Denied exec of /home/test/run-python Reason: file in non-root-owned

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